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Open AccessArticle

Differential Mechanisms of Photosynthetic Acclimation to Light and Low Temperature in Arabidopsis and the Extremophile Eutrema salsugineum

1
Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada
2
Department of Biochemistry, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
3
Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
*
Author to whom correspondence should be addressed.
Present Address: Agriculture and Agri-Food Canada, Lacombe Research and Development Centre, 1 Research Road, P.O. Box 29, Beaverlodge, AB T0H 0C0, Canada.
These authors contributed equally to this work.
§
Present Address: University of Saint Katherine, 1637 Capalina Road, San Marcos, CA 92069, USA.
Plants 2017, 6(3), 32; https://doi.org/10.3390/plants6030032
Received: 14 June 2017 / Revised: 19 July 2017 / Accepted: 1 August 2017 / Published: 9 August 2017
Photosynthetic organisms are able to sense energy imbalances brought about by the overexcitation of photosystem II (PSII) through the redox state of the photosynthetic electron transport chain, estimated as the chlorophyll fluorescence parameter 1-qL, also known as PSII excitation pressure. Plants employ a wide array of photoprotective processes that modulate photosynthesis to correct these energy imbalances. Low temperature and light are well established in their ability to modulate PSII excitation pressure. The acquisition of freezing tolerance requires growth and development a low temperature (cold acclimation) which predisposes the plant to photoinhibition. Thus, photosynthetic acclimation is essential for proper energy balancing during the cold acclimation process. Eutrema salsugineum (Thellungiella salsuginea) is an extremophile, a close relative of Arabidopsis thaliana, but possessing much higher constitutive levels of tolerance to abiotic stress. This comparative study aimed to characterize the photosynthetic properties of Arabidopsis (Columbia accession) and two accessions of Eutrema (Yukon and Shandong) isolated from contrasting geographical locations at cold acclimating and non-acclimating conditions. In addition, three different growth regimes were utilized that varied in temperature, photoperiod and irradiance which resulted in different levels of PSII excitation pressure. This study has shown that these accessions interact differentially to instantaneous (measuring) and long-term (acclimation) changes in PSII excitation pressure with regard to their photosynthetic behaviour. Eutrema accessions contained a higher amount of photosynthetic pigments, showed higher oxidation of P700 and possessed more resilient photoprotective mechanisms than that of Arabidopsis, perhaps through the prevention of PSI acceptor-limitation. Upon comparison of the two Eutrema accessions, Shandong demonstrated the greatest PSII operating efficiency (ΦPSII) and P700 oxidizing capacity, while Yukon showed greater growth plasticity to irradiance. Both of these Eutrema accessions are able to photosynthetically acclimate but do so by different mechanisms. The Shandong accessions demonstrate a stable response, favouring energy partitioning to photochemistry while the Yukon accession shows a more rapid response with partitioning to other (non-photochemical) strategies. View Full-Text
Keywords: adaptive (phenotypic) plasticity; Arabidopsis thaliana; cold acclimation; Eutrema salsugineum; low temperature; photoinhibition; photosynthesis; photosynthetic acclimation adaptive (phenotypic) plasticity; Arabidopsis thaliana; cold acclimation; Eutrema salsugineum; low temperature; photoinhibition; photosynthesis; photosynthetic acclimation
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MDPI and ACS Style

Khanal, N.; Bray, G.E.; Grisnich, A.; Moffatt, B.A.; Gray, G.R. Differential Mechanisms of Photosynthetic Acclimation to Light and Low Temperature in Arabidopsis and the Extremophile Eutrema salsugineum. Plants 2017, 6, 32.

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